InputContainer: Fall cleanup ;).

Get rid of the doc & seqtext fields, as they are not actually used (nor
are they particularly useful, the event handler's name should be pretty
self-explanatory).

Also, tweak the key_events documentation to highlight the quirks of the
API, especially as far as array nesting is involved...

Random drive-by cleanup of the declarations of key_events & ges_events
to re-use the existing instance object (now that we know they're sane
;p) for tables with a single member (less GC pressure).

frontend/apps/reader/modules/readerfont.lua

@@ -34,15 +34,17 @@ function ReaderFont:init()
     if Device:hasKeyboard() then
         -- add shortcut for keyboard
         self.key_events = {
-            ShowFontMenu = { {"F"}, doc = "show font menu" },
+            ShowFontMenu = { { "F" } },
             IncreaseSize = {
                 { "Shift", Input.group.PgFwd },
-                doc = "increase font size",
-                event = "ChangeSize", args = 0.5 },
+                event = "ChangeSize",
+                args = 0.5
+            },
             DecreaseSize = {
                 { "Shift", Input.group.PgBack },
-                doc = "decrease font size",
-                event = "ChangeSize", args = -0.5 },
+                event = "ChangeSize",
+                args = -0.5
+            },
         }
     end
     -- Build face_table for menu